SEMI-CONTINUOUS CASTING EQUIPMENT FOR THE MANUFACTURE OF ROLL INGOTS

Abstract: Direct chill, semi-continuous casting equipment for the manufacture of roll ingots. The equipment comprises an upper metal reservoir (10), a casting die or die (2) fitted below the metal reservoir with an inlet and an outlet and a vertically moveable base (7) fitted at the outlet with a casting shoe (5) which is designed to bear against the outlet at the start of a casting cycle. The casting shoe is mounted as a moveable shoe (at 6) on the base (7) and is designed to be locked in relation to the base when it has been brought into a centred position in relation to the casting die (2). Furthermore, corresponding centring devices (3, 4, 8) for the casting die and the casting shoe respectively are fitted for centring the casting shoe in relation to the casting die.

Description: Semi-continuous casting equipment for the manufacture of roll ingots The present invention concerns direct chill, semi-continuous casting equipment for the manufacture of roll ingots in metal, primarily aluminium, comprising an upper metal reservoir, a casting die with an inlet and an outlet fitted below the metal reservoir, and a moveable base fitted to the outlet with a casting shoe which is designed to bear against the outlet at the start of a casting cycle. In connection with the manufacture of metal castings of small dimensions, for example ingots for extrusion purposes, a self- centring casting shoes is used which is based on a simple principle in which the casting shoes rest on well-greased bases. The casting dies or chills are fitted with a guide edge which guides each of the casting shoes into place in the chill when the moveable base is moved up. Because of the small dimensions and low weight of the casting shoes, this system functions very satisfactorily. In connection with roll-ingot casting, however, a similar system will not function as the casting shoe (just one) for this type of casting equipment has a considerably larger bearing surface and is considerably heavier. In connection with roll-ingot casting it is common to use manual centring of the casting shoe by means of a bar. This results in damage to both the casting shoe and the casting die as a consequence of the bar, and because the edge of the shoe touches the die wall. This damage in the shape of scratches and cuts on the die wall and casting shoe respectively can, in turn, result in surface defects in the roll-ingot wor pieces and, in the worst case, in leakage between the casting die and the casting shoe and in damaged workpieces. Recently, a solution has been introduced on the market in which the casting shoe is stationary, but in which the casting die itself is centred around the shoe. The casting die is thus mounted as a moveable die and designed to be moved by means of eight pneumatic cylinders fitted at each of the corners of the die. As the pneumatic cylinders are operated manually, this solution also involves a risk of the edge of the casting shoe damaging the casting die. In addition, such a solution with a moveable casting die in which a large number of pneumatic cylinders are used is very expensive in terms of construction and maintenance. With the present invention a solution with direct chill casting equipment has been arrived at which provides safe and accurate centring of the casting shoe in relation to the casting die, thus eliminating damage to these parts. Furthermore, a solution has been arrived at which can be manufactured at a reasonable price and which is simple and inexpensive to maintain. In accordance with the present invention the casting equipment is characterized in that the casting shoe is mounted as a moveable shoe on the base and is designed so that it can be locked in relation to the base when it has been placed in the centred position in relation to the casting die. For centring the casting shoe in relation to the casting die, corresponding centring devices is provided for the casting die and the casting shoe respectively as defined in the attached claim 1. In relation to a preferred embodiment as defined in claim 2, the support between the base and the casting shoe can consist of one or more air cushions. The base and the shoe are interlocked by the air supply to the air cushions being shut off so that the casting shoe is lowered down and rests directly on the base after the casting shoe has been brought into the correct position in relation to the casting die. In accordance with another preferred embodiment as defined in claim 4 the centring devices can consist of at least two conic guide pins which correspond to two guide sleeves fitted on the casting die or vice versa. The other dependent claims define further advantageous features of the invention. In the following the invention will be described in further detail by means of examples and reference to drawings in which Fig. 1 gives a schematic outline of casting equipment for the manufacture of roll ingots in accordance with the invention and Fig. 2 shows the same as in Fig. 1 but with the casting shoe for the equipment shown in different positions. Direct chill, semi-continuous casting equipment 1 for the manufacture of roll ingots, so-called DC (Direct Chill) casting equipment consist roughly, as shown in Fig. 1, of an upper metal reservoir 10 which is encased by a casting die 2 and a vertically moveable base 7 with a casting shoe 5 which is designed to bear against the outlet of the casting die at the start of a casting operation. Devices for water chilling of the metal during the casting operation, possibly devices for the supply of gas or lubricant to the casting die, and devices for vertical movement of the base are not shown in the drawing as they do not form part of the invention and are unnecessary for an understanding of it. As mentioned, the casting shoe 5 bears against the casting die outlet and forms the base of the outlet at the start of a casting operation. Liquid metal is supplied to the reservoir 10 from above, and as soon as the metal begins to harden at the casting shoe 5, the shoe is lowered downward together with the base. At the same time water is supplied through a slot (not shown) which chills the metal further so that a long metal workpiece is formed with a cross-section which is defined by the opening in the casting die. When the base 7 has reached its bottom position, the casting operation stops, the cast metal workpiece is removed, and the base 7 with the casting shoe 5 is moved back to its original position for commencement of a new casting operation. The special feature of the present invention is that a support and a centring device (3, 4, 6) are fitted between the base and the casting shoe which make it possible to centre the casting shoe securely and in an accurate position in relation to the casting die. In the example shown in the drawing the support consists of air cushions 6 fitted between the casting shoe and the base. The cushions can be located adequately in recesses 9 in the casting shoe 5 or the base 7 so that they are located completely in these recesses and so that the casting shoe rests directly (metal against metal) on the base when the air supply is shut off. The centring device consists of at least two (one at either end of the casting shoe) guide pins 3 protruding downward from the casting die and which are designed to correspond to guide sleeves or openings on the casting shoe. The pins 3 and the sleeves 4 may be fitted vice versa. Both the pins 3 and the sleeves or openings 4 have conically shaped parts 13, 14 which guide the two parts into an interlocking position with each other. The guide sleeve is fitted in detachable and adjustable juts or brackets 8 so that they can be adjusted individually in advance in relation to the casting shoe to ensure that the casting shoe is in the correct position during the centring operation. Instead of pins and sleeves, another centring device may be used, if required, for example wedges with bevel edges pointing downwards from the casting die which bear against the outside of the casting shoe. The casting shoe 5 is, moreover, fitted with a downward project¬ ing edge 11 which prevents it from being displaced too much sideways in relation to the base 7, and thus ensures that the guide pins are inserted into the sleeve. In connection with centring the casting shoe 5 into the correct position before the casting operation, the base is moved upwards, and air or another gas is supplied (not shown in further detail) to the air cushions 6. The casting shoe will consequently move upwards and out of the friction interlocking with the base as shown in Fig. 2. The casting shoe can thus easily be moved sideways, and the impact on the guide pins 3 and the guide sleeves 4 will be minimal. The centring operation can now be performed by raising the base to an upper level at which the upper part of the casting shoe is inside and slightly protruding from the lower edge of the casting die or die 2 as shown in Fig. 3. The air or gas supply is subsequently shut off so that the casting shoe sinks down a few millimetres and again interlocks frictionally with the base as shown in Fig. 4. It is important that the casting shoe is not displaced in relation to the base during the casting operation as such displacement would result in the casting workpiece being destroyed. Friction locking, i.e. that the casting shoe rests directly on the base, will probably be sufficient for most casting dies to keep the casting shoe in place. As an extra measure, however, an extra locking device, such as a clamp device which presses the casting shoe against the base, can be fitted. The whole centring operation can be performed automatically by means of a Logic control guide unit and electrical switching devices and components which are generally known, and which will not be mentioned further here. In the example shown in the figures and described in the above it has been indicated that the support between the casting shoe and the base comprises two air cushions 6. It should be noted that the invention as defined in the claims is not limited to two cushions but can be used with one cushion or more than two cushions. Moreover, the invention is not limited to the use of cushions. Thus, for example, a ball support can be used which can be raised mechanically in order to lift the casting shoe from the base during the centring operation. Other types of support may possibly also be used but the condition for this is that they give so little friction that the casting shoe can easily be moved on the base.

Claims: Claims Direct chill, semi-continuous casting equipment for the manufacture of roll ingots consisting of an upper metal reservoir (10) , a casting die fitted below the metal reservoir (2) with an inlet and an outlet, and a vertically moveable base (7) fitted to the outlet with a casting shoe (5) which is designed to bear against the outlet at the start of a casting cycle, c h a r a c t e r i z e d i n that the casting shoe is mounted as a moveable shoe (at 6) on the base (7) and is designed to be locked in relation to the base when it has been brought into a centred position in relation to the casting die (2) , whereas for the centring of the casting shoe in relation to the casting die corresponding centring devices (3, 4, 8) are fitted for the casting die and the casting shoe respectively. Casting equipment in accordance with claim 1, c h a r a c t e r i z e d i n that the support between the base and the casting shoe consists of one or more air cushions (6) , whereas the base and the shoe are interlocked by the air supply to the cushions being shut off so that the casting shoe is lowered and rests directly on the base after the casting shoe has been placed in the correct position in relation to the casting die. Casting equipment in accordance with claim 1, c h a r a c t e r i z e d i n that the cushions are fitted in recesses (9) in the base (7) or the casting shoe (15) . Casting equipment in accordance with claim 1, c h a r a c t e r i z e d i n that the support between the base and the casting shoe consists of a ball support which can be raised mechanically in order to lift the casting shoe from the base during the centring operation. Casting equipment in accordance with claim 1, c h a r a c t e r i z e d i n that the centring devices consist of at least two guide pins (3) fitted on the casting shoe with conically shaped parts which correspond to two guide sleeves (4) with conical parts fitted on the casting die or vice versa. Casting equipment in accordance with claim 4, c h a r a c t e r i z e d i n that the guide sleeves (4) are fitted in brackets or juts (8) which are adjustable in relation to the casting shoe or the casting die. Casting equipment in accordance with claims 1-5, c h a r a c t e r i z e d i n that the casting shoe is fitted with a downward projecting edge (11) which projects outwards and down past the upper part of the base (7) .

Inventors: NAESS HARALD JR, STEEN IDAR, NAESS, HARALD, JR., STEEN, IDAR
Applicants: NAESS HARALD JR, NORSK HYDRO AS, STEEN IDAR, NAESS, HARALD, JR., NORSK HYDRO A.S, STEEN, IDAR
Application year: 1994
Main classification: B22D11
IPC codes: B22D11